1. Field of the Invention
The present invention relates to a radio wave receiver comprising an antenna and a tuning unit.
2. Description of Related Art
Conventionally, there is suggested a communication apparatus which makes the resonance frequency of an antenna tune to the frequency of a desired wave by changing frequency characteristic of a tuning circuit connected to the antenna (for example, Japanese Patent Application Laid-Open Publication No. 11-312958 and Japanese Patent Application Laid-Open Publication No. 2000-231609). Further, Japanese Patent Application Laid-Open Publication No. 11-312958 discloses a technique in which the size of tuning capacitance can be switched continuously and finely by carrying out weighting to the capacitance values of a plurality of resonance condensers which can be connected and can be cut-off in an antenna circuit to arbitrarily switch the resonance condensers.
When the adjustment of tuning capacitance can be finely set, a long time is required to search for the optimum setting condition by carrying out switching of the tuning capacitance one step at a time for the entire adjustable range because the number of steps to switch the setting increases.
An object of the present invention is to provide a radio wave receiver which can shorten the process time by effectively carrying out the switching of the setting of the tuning circuit when searching for the optimum setting condition of the tuning circuit.